Odour Control in Starch Processing Plants: A Practical Guide

Have you ever passed by a starch factory? If yes, then you must have encountered that strong, sour smell which sometimes resembles that of rotten eggs. Now think about what challenges people who live near that factory, live in that locality, or work inside that factory will have to face. People who are bothered by the smell can also complain and you can have the pressure from regulators and the community.

Yes, it is true that starch processing is very important for the food, paper and textiles industries, but the by-products of soaking, drying, and wastewater treatment create odours that are hard to ignore. But, don't worry, you can control this odor. All you need is the right mix of engineering, biology and smart chemical solutions.

In this blog, let’s break down where these odours come from, why they matter, and the practical solutions that starch plants are using today.

Why Starch Plants Smell: The Main Sources

Not all parts of a starch plant smell the same. Here are the usual suspects:

• Wastewater and lagoons: When carbohydrates and proteins from food waste get into wastewater tanks, they soon stop using oxygen. That's when gasses like ammonia (NH₃) and hydrogen sulfide (H₂S) develop, which smell like rotten eggs or something else strong.

  
  

• Steeping tanks (in corn wet milling): The maize kernels are steeped in a mixture of sulfur dioxide (SO₂) and water. This helps with the grinding process, but if the tanks aren't sealed properly, it lets out a strong and bad smell.

  
  

• Dryers: Drying corn gluten meal, potato pulp, or germ at high temperatures creates a mix of VOCs (volatile organic compounds). The exhaust from the dryer is one of the strongest and most recognizable smells.

Let’s Understand The Science of the Smell

What exactly are people smelling around these plants? A few common culprits:

• Hydrogen sulfide (H₂S): Think “rotten eggs.” Detectable even at extremely low concentrations.

• Ammonia (NH₃): A sharp, choking smell that also causes corrosion in equipment.

• Sulphur dioxide (SO₂): Used in steeping, known for its sharp, acidic odour.

• Volatile organic compounds (VOCs): Aldehydes, amines, and sulfur compounds that add sour or pungent notes.

Even tiny amounts of these gases can trigger complaints. That’s why control systems need to be designed with precision.

Why Controlling Odour Matters?

For starch producers, odour control isn’t just about making the plant smell better. It has bigger consequences:

• Community trust: Neighbours don’t want to live with constant odours. Complaints can quickly escalate.

• Regulatory compliance: Many countries have strict rules about carbon oxides, hydrogen sulfide, and volatile organic compounds (VOCs). If you don't control odors, you could get fined or have to close.

• Workplace comfort: People who work in smelly environments experience fatigue, an increased risk of illness, and a depressed mood.

• Reputation and growth: A plant known for pollution struggles to win contracts or expand capacity.

First Step: Capture the Odour

You are unable to treat something that you have not captured. After ensuring that gases are gathered before they escape, the first stage in smell management is to ensure that they are collected. In most cases, this indicates:

• Enclosing steeping tanks and open wastewater units.

• Installing hoods and ducts over dryers.

• Keeping areas under negative pressure so smells don’t leak out.

Once the odour is captured, it can be directed to treatment systems where the real work begins.

Odour Control Technologies that Work

Different odour sources need different solutions. Here are the most effective options:

• Wet scrubbers: It works best to soak up smells, especially carbon monoxide. An alkaline scrubber gets rid of acidic gasses, whereas other types can get rid of NH3 and H2S.

• Biofilters and biotrickling filters: Microbes "eat" the smelly gases in these living systems, which are also home to other creatures. They are very useful for smells that come from treating wastewater, and they are cheap in the long run.

• Activated carbon or dry media filters: Great for polishing or for dealing with transitory spikes. They can take in gases that the initial treatment doesn't get rid of.

• Thermal oxidisers: Used on dryers, these systems burn VOCs at high temperatures, destroying odours almost completely. With heat recovery, they can also improve energy efficiency.

• Chemical oxidation in wastewater: Adding agents like permanganate can help break down odorous compounds in treatment plants.

Tackling Odours at the Source: Wastewater Fixes

Since wastewater is often the biggest smell generator, improving treatment goes a long way. Options include:

• Covering lagoons so gases can be collected and treated instead of drifting into the air.

• Anaerobic digestion with biogas recovery, which not only reduces odour but also produces renewable energy.

• Better process control, including pH balancing, nutrient management, and aeration, to prevent dead zones where foul gases form.

• Equalisation tanks that reduce sudden load variations and stabilise treatment.

A cleaner wastewater system means fewer complaints and lower overall odour control costs.

Measuring What You Can’t See (or Smell)

To know whether odour control is working, plants rely on monitoring systems:

• Gas sensors for H₂S, NH₃, and SO₂.

• VOC monitors for compounds like acetaldehyde.

• Fence-line monitoring stations to check community impact.

• Regular odour surveys to document improvements.

This data helps operators fine-tune systems and provides proof of compliance.

Matching Solutions to Odour Sources

Here’s a simple rule of thumb:

• Steeping/SO₂: Enclose + alkaline scrubber.

• Dryers: Thermal oxidiser.

• Wastewater/WWTP air: Biofilter or biotrickling filter.

• Polishing stage: Activated carbon for extra assurance.

By combining these systems, starch plants can eliminate odours from every major source.

The Payoff of Doing It Right

When starch plants invest in proper odour control, the results speak for themselves:

• Biofilters can cut H₂S and NH₃ odours by more than 90%.

• Thermal oxidisers routinely destroy over 99% of VOCs from dryers.

• Covered lagoons with gas recovery can completely eliminate surface odours and generate usable energy.

The outcome? Fewer complaints, better community relations, and a stronger license to operate.

How Amalgam Biotech Supports Starch Plants?

Amalgam Biotech knows that no two starch plants are the same. A maize wet mill that is having trouble with sulfur dioxide needs a completely different approach than a potato starch business that is coping with bad smells from waste.

That’s why we design custom systems that combine the right mix of:

• Wet scrubbers for steeping and mixed gases.

• Biofilters and biotrickling filters for wastewater odours.

• Dry media systems for polishing.

• Process-side improvements in wastewater treatment.

Our goal is to help starch factories manage smells in a way that is reliable and long-lasting, meets the needs of regulators, makes communities happy, and keeps operations running smoothly.

Explore our Odour Control Solutions here.

Conclusion

Controlling smells in starch processing isn't just about making the smell nicer; it's also about following the rules, being efficient, and keeping your good name. By trapping pollutants, utilizing the right treatment technology, and fixing wastewater problems at the source, plants can go from being a source of complaints to being known for their ecologically friendly operations.

At Amalgam Biotech, we apply our understanding of biotechnology, chemical research, and engineering to build robust systems that get rid of smells for good. It's time to take care of the scents that are hurting your business.